1. Field of the Invention
The present invention relates to an image forming apparatus for forming an image, its operation recording method, and a storage medium.
2. Description of the Related Art
A method for investigating a cause of a failure in a network communication device by collecting packets flowing through a network communication path is generally known. According to the general method, a device dedicated to packet acquisition is connected to a line concentrator, and a manager of the communication device collects packets flowing through a local area network (LAN) by using this dedicated device.
The manager analyzes, among the collected packets, the data of a packet transmitted/received by the network communication device, which is the investigation target. As a result of the analysis, the manager identifies a place which has received unprescribed data or a place where a delay of response to a received packet has occurred. To determine whether such a place is a cause of the failure, the manager carries out cause investigation such as transmission of the same packet to the network device to reproduce and confirm the failure, or conducts analysis of a source code responsible for communication of the network device.
A network communication device having a packet acquisition function has recently become popular. This function enables acquisition of a packet without using any device dedicated to packet collection. Thus, even when correct packet collection cannot be carried out even if a dedicated device is connected, for example, in an environment where a switching hub has been introduced, packets can be collected. As a result, packet collection has generally been used when a failure of a communication device occurs or packet information investigation is performed.
The log data of an obtained network packet is stored in a nonvolatile memory such as a magnetic disk so that the stored log data can be acquired when the log information is investigated at a later date. Thus, the manager can check what data have been processed in what order when the failure occurs, at a later date. In this case, the log data records contents of a performed operation, transmitted/received data, or a date and time when the operation or data transmission/reception is carried out.
Such technique is important because it enables a user of the device to receive a quick description and appropriate countermeasures when a device failure occurs.
In order to analyze the failure, checking of the following information from the log data is more important than checking the log data when the device normally operates: information indicating what data have been processed in what order and with what size and frequency just before/after occurrence of a device failure or a performance reduction.
Further, it is important to check a processing speed or a flow rate of data relating to the device for a fixed time, or investigate how often the device is accessed by the data such as a packet that is not directly associated with the device.
It is important in the function of storing the log data such as a network packet that “necessary data are correctly stored in correct order with correct sizes, at timing just before/after occurrence of a failure or at timing desirable for acquisition of log data”. It is publicly known that an access speed of a volatile memory is faster than that of a nonvolatile memory. Thus, in view of improvement of processing performance and a life of the nonvolatile memory dependent on an upper limit of a number of accessing times to the nonvolatile memory, when the data is stored in the nonvolatile memory, storing the data first in the volatile memory and then storing the data in the nonvolatile memory may be employed.
A possible problem in the case of storing the log data in the nonvolatile memory by using this method is that a user may turn off power of the device while the log data is being acquired and stored in the nonvolatile memory. If that happens, the log data stored in the volatile memory is lost.
The lost data is no longer stored in the nonvolatile memory. Consequently, the object of “correctly storing the log data necessary for failure analysis, just before/after occurrence of the failure of the device or at the time of a performance reduction” cannot be achieved. This means a possible loss of the important log data that is to be an investigation target.
A method has recently been employed which maintains a conductive state of the device for a certain time after receiving a power cutoff signal by using an auxiliary battery or a charge memory at the time of power cutoff and storing the data held in the volatile memory in the nonvolatile memory while maintaining the conductive state. Japanese Patent Application Laid-Open No. 11-25007 discusses use of a random access memory (RAM) backed-up by a battery, which is triggered by NMI interruption of a central processing unit (CPU) at the time of power cutoff of the device. Thus, the stored data of the RAM is saved by keeping the RAM in the conductive state for a certain time to prevent a data loss of the volatile memory.
However, in the above example, cost of preventing the data loss of the volatile memory is very high. Thus, when the log data storing function is used only for investigation, the cost should preferably be kept as low as possible.